The Virus is a new strain of influenza that appeared in between seasons 2 and 3 which has nearly decimated the population of vampires.
It's unknown where or how the virus came from, why it has such an effect on vampires, or why such a disease had not appeared in the past, but it is possible that it was not a naturally occuring epidemic.
It was no worse than the common flu for humans, but the antibodies left behind in the blood of people infected by it make any vampire that drinks from them terminally ill.
The disease advances rapidly in vampires, with symptoms appearing only a few hours after infection. Black, splotchy lesions appear on the skin, the victim begins coughing and has difficulty breathing, and becomes weaker and weaker as the human antibodies attack the vampiric tissue of the host. Death typically occurs within a few days of initial infection.
CureEditWhile there is no true 'cure' for the virus, it is possible for vampires to innoculate themselves against the disease by drinking werewolf blood. The effect that werewolf blood has on vampires is implied to be a milder version of the effects of the Plague, which means that werewolf blood builds up a resistance to the disease ahead of time, like a vaccine.
Side EffectEditHowever, while the vampire may be cured of the effects of the virus, there is an apparent negative side effect to a vampire that has ingested werewolf blood, being that if the vampire later tries to turn a human into another vampire, the new vampire will instead become an abomination as a result of the mixed blood.
Aidan unintentionally drank from Erin only a few weeks prior to catching the disease. After he got sick, the disease ran its course, only to be fought off by his immunity before death could occur.
- Mother (unconfirmed)
- The Dutch (most killed by Liam)
- Aidan Waite (cured)
- Carlos Boyd (killed by Liam)
- James Bishop (Alternate Timeline)
- It's unknown if the virus was global since the origins of the flu is unknown, but some viewers believe the virus likely was global, seeing as it was mentioned that the vampires were apparently driven to near-extinction by the virus.